If only the pic was bigger... (I know you mentioned that was the biggest you had) I want to see what that silver metal piece looks like running down the center horizontally about midway... did that make sense?
or using YT's train of thought---an adjustable squeegie that fits into tight corners?? Or better yet, an adjustable back scratcher? Ha! Is it too early for dimensions yet?
I`m still going with the idea that it fits on something else, perhaps a runner or guide, but perhaps that "handle thing" isn`t for a hose, it might be to tighten it to a rail when it`s in place.